In order to optimize FIFO access, especially on m_can cores attached
to slow busses like SPI, in patch
| e39381770ec9 ("can: m_can: Disable IRQs on FIFO bus errors")
bulk read/write support has been added to the m_can_fifo_{read,write}
functions.
That change leads to the tcan driver to call
regmap_bulk_{read,write}() with a length of 0 (for CAN frames with 0
data length). regmap treats this as an error:
| tcan4x5x spi1.0 tcan4x5x0: FIFO write returned -22
This patch fixes the problem by not calling the
cdev->ops->{read,write)_fifo() in case of a 0 length read/write.
Fixes: e39381770ec9 ("can: m_can: Disable IRQs on FIFO bus errors")
Link: https://lore.kernel.org/all/20220114155751.2651888-1-mkl@pengutronix.de
Cc: stable(a)vger.kernel.org
Cc: Matt Kline <matt(a)bitbashing.io>
Cc: Chandrasekar Ramakrishnan <rcsekar(a)samsung.com>
Reported-by: Michael Anochin <anochin(a)photo-meter.com>
Signed-off-by: Marc Kleine-Budde <mkl(a)pengutronix.de>
---
drivers/net/can/m_can/m_can.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 5b47cd867783..1a4b56f6fa8c 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -336,6 +336,9 @@ m_can_fifo_read(struct m_can_classdev *cdev,
u32 addr_offset = cdev->mcfg[MRAM_RXF0].off + fgi * RXF0_ELEMENT_SIZE +
offset;
+ if (val_count == 0)
+ return 0;
+
return cdev->ops->read_fifo(cdev, addr_offset, val, val_count);
}
@@ -346,6 +349,9 @@ m_can_fifo_write(struct m_can_classdev *cdev,
u32 addr_offset = cdev->mcfg[MRAM_TXB].off + fpi * TXB_ELEMENT_SIZE +
offset;
+ if (val_count == 0)
+ return 0;
+
return cdev->ops->write_fifo(cdev, addr_offset, val, val_count);
}
--
2.34.1
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 7c8a4742c4abe205ec9daf416c9d42fd6b406e8e Mon Sep 17 00:00:00 2001
From: David Matlack <dmatlack(a)google.com>
Date: Thu, 13 Jan 2022 23:30:17 +0000
Subject: [PATCH] KVM: x86/mmu: Fix write-protection of PTs mapped by the TDP
MMU
When the TDP MMU is write-protection GFNs for page table protection (as
opposed to for dirty logging, or due to the HVA not being writable), it
checks if the SPTE is already write-protected and if so skips modifying
the SPTE and the TLB flush.
This behavior is incorrect because it fails to check if the SPTE
is write-protected for page table protection, i.e. fails to check
that MMU-writable is '0'. If the SPTE was write-protected for dirty
logging but not page table protection, the SPTE could locklessly be made
writable, and vCPUs could still be running with writable mappings cached
in their TLB.
Fix this by only skipping setting the SPTE if the SPTE is already
write-protected *and* MMU-writable is already clear. Technically,
checking only MMU-writable would suffice; a SPTE cannot be writable
without MMU-writable being set. But check both to be paranoid and
because it arguably yields more readable code.
Fixes: 46044f72c382 ("kvm: x86/mmu: Support write protection for nesting in tdp MMU")
Cc: stable(a)vger.kernel.org
Signed-off-by: David Matlack <dmatlack(a)google.com>
Message-Id: <20220113233020.3986005-2-dmatlack(a)google.com>
Reviewed-by: Sean Christopherson <seanjc(a)google.com>
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7b1bc816b7c3..bc9e3553fba2 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1442,12 +1442,12 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root,
!is_last_spte(iter.old_spte, iter.level))
continue;
- if (!is_writable_pte(iter.old_spte))
- break;
-
new_spte = iter.old_spte &
~(PT_WRITABLE_MASK | shadow_mmu_writable_mask);
+ if (new_spte == iter.old_spte)
+ break;
+
tdp_mmu_set_spte(kvm, &iter, new_spte);
spte_set = true;
}